README.md: add some information

README.md

@@ -17,18 +17,20 @@ Compiling Browser
 
 Browser depends on the following components:
 
- * Gtk+ 2 or 3
+ * Gtk+ 2.4 or newer, or Gtk+ 3.0 or newer
  * DeforaOS libDesktop
  * an implementation of `make`
  * gettext (libintl) for translations
  * DocBook-XSL for the manual pages
  * GTK-Doc for the API documentation
 
-With GCC, this should then be enough to compile and install Browser:
+With these installed, the following command should be enough to compile and
+install Browser on most systems:
 
     $ make install
 
-To install (or package) Browser in a different location:
+To install (or package) Browser in a different location, use the `PREFIX` option
+as follows:
 
     $ make PREFIX="/another/prefix" install
 
@@ -37,6 +39,11 @@ instance:
 
     $ make DESTDIR="/staging/directory" PREFIX="/another/prefix" install
 
+The compilation process supports a number of other options, such as OBJDIR for
+compilation outside of the source tree for instance.
+
+On some systems, the Makefiles shipped may have to be re-generated accordingly.
+This can be performed with the DeforaOS configure tool.
 
 Documentation
 -------------
@@ -48,6 +55,19 @@ DocBook-XSL to be installed for conversion to the HTML or man file format.
 Likewise, the API reference for Browser (plug-ins) is available in the
 `doc/gtkdoc` folder, and is generated using gtk-doc.
 
+Extending Browser
+-----------------
+
+Plug-ins for the Browser program can be written according to the API definitions
+installed and found in `<Desktop/Browser.h>` (in the source code in the
+`include/Browser.h` file).
+
+A sample plug-in can be found in `src/plugins/template.c`.
+
+Further plug-ins may also be found in the
+[DeforaOS Integration](https://www.defora.org/os/project/4339/Integration)
+project.
+
 Distributing Browser
 --------------------